(a) Technical Field
The inventive concept relates to a display device and a driving method thereof.
(b) Description of the Related Art
A display device is required for a computer monitor, a television, a mobile phone, and the like, which are widely used today. Display devices include a liquid crystal display (LCD) and an organic light emitting diode (OLED) display.
The display device generally includes a graphic controller (GPU, graphics processing unit), a display panel including a plurality of pixels including a switching element and a plurality of signal lines, a data driver generating a plurality of gray voltages and applying a gray voltage corresponding to an input image signal among the generated gray voltages to a data line as a data signal, a gate driver generating and applying a gate signal to a gate line, and a signal controller controlling the gate driver and the data driver.
The graphic controller receives image information from the outside, generates an input image signal and an input control signal based on the image information, and transmits the input image signal and the input control signal to the signal controller. The signal controller appropriately processes the input image signal based on the input control signal to generate an output image signal and several control signals. The data driver selects the gray voltage corresponding to the output image signal input from the signal controller and applies it to the data line of the display panel as the data voltage.
The image displayed on the display device may be largely classified into a still image and a moving image. The display panel displays images of various frames per second, and if the image signals of the adjacent frames are the same as each other, the display panel may display the stationary image, while if the image signals of the adjacent frames are different from each other, the display panel may display the motion picture. The signal controller receives the input image signal for every frame from the graphics processing unit. In the case where the stationary image is displayed, the same input image signal is received for every frame. Thus, unnecessary power consumption may be increased. Accordingly, it is necessary to reduce power consumption by operating the display panel with a low power mode when displaying the still image. For example, when displaying the still image, the step of transmitting the same input image signal from the graphic controller to the signal controller may be omitted. Particularly, demand for a low power consumption device has increased for the display device used in a portable terminal such as a laptop computer and a tablet computer.
Generally, a bit number of the input image signal that is processed in the graphic controller and a bit number that can be processed in the signal controller are the same, and a bit number of the output image signal that is processed in the signal controller and a bit number that can be processed in the data driver are the same. However, when the bit numbers of the input image signal, the bit number that can be processed in the signal controller and the bit number that can be processed in the data driver are different, a dithering method of reconfiguring the image signal may be used. The dithering method uses only upper bits corresponding to the bit number that can be processed in the signal controller or the data driver among the bits of the input image signal or the output image signal, and modify the upper bits to represent lower bits using dithering patterns. For example, the dithering pattern may be a compensation value group corresponding to pixels. A resolution of a gray scale image may be increased by minutely controlling the luminance by using this dithering method. For this purpose, the display device may store a plurality of different dithering patterns for each gray and each frame for the dithering. The dithering patterns may be repeated periodically, for example, the dithering patterns may be repeated every several frames, and this cycle is referred to as a dithering cycle.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept and therefore it may contain information that does not form the prior art.